Historical district faces the challenge of decline in vitality in Dabaodao, Qingdao, this paper research the vitality of its public space from the macro and micro levels. Based on POI data and the traditional investigation method of PSPL, the point density analysis of big data and the qualitative and quantitative analysis method of traditional research data is used for the results. The study found that the decline of public space, the lack of modern life elements, and the incoordination with the surrounding vitality space are the main reasons for the decline of vitality in the historic district of Dabaodao. Combined with case analysis and its own historical and cultural attributes, this paper proposes specific strategies for improving vitality from three aspects: the material cultural space, cultural function space, and cultural service space of the historical district of Dabaodao.